Typical asphalt-based roofing shingles include a base mat that is impregnated with asphalt and covered with a layer of ceramic granules. To provide an aesthetic appearance, a blend of colored granules is applied to the exposed tab portions of the shingles, which are visible when the shingles are installed on a roof. However, in an effort to reduce cost, granules of a single color or granules of a lesser quality are applied to the headlap portions of the shingles, which are normally covered when the shingles are installed on a roof. Because the headlap portion is not exposed or visible upon installation, the use of granules of a single color or lesser quality has no impact on the appearance or performance of the shingle.
The use of different types of granules on the tab portion and headlap portion results in waste. When the blend of colored granules is applied to the tab portion, not all of the granules are adhered to the shingle. Instead, a portion of these granules do not become adhered to the shingle and fall below. The same is true for the granules that are applied to the headlap portion. Due to the close spatial proximity in which the more costly tab granules and less costly headlap portion granules are applied to the shingle, all of the granules which do not adhere to the shingle fall to a common area below and become mixed. While this mix of backfall granules can be reused, because the headlap granules are mixed in with the tab granules, the recovered granules cannot be reapplied to the tab portion. To do so would result in tab portions of an inconsistent color and visual appearance. Rather, the recovered backfall granules, which include a mix of the more costly tab granules and the less costly headlap granules, can only be reapplied to the headlap portion. Thus, a percentage of the more costly blended colored granules do not end up on the intended tab portion of the product, but instead end up on the headlap portion. As such, this is viewed as a waste and inefficiency in the production process.
The granules applied to asphalt-based shingles can account for a significant part of the overall weight of the shingles. The heavier the shingles, the more difficult it can be for installers to handle and maneuver bundles of the shingles and the more costly it is to transport the shingles via truck or rail. Further, the heavier the shingles, the greater the possibility that a roof structure may experience a failure due to a snow load or other overloading scenarios.
Accordingly, a need exists for a shingle that does not require separate headlap granules and tab granules so that substantially all of the blended color tab granules that do not initially become adhered to one shingle may be recovered and reapplied to the tab portion of another shingle during the manufacturing process. An additional need exists for an asphalt-based shingle that is lighter in weight. A further need exists for a shingle that can be manufactured on a more cost effective and efficient basis.